Is Alzheimer's disease preventable? A review of two decades of epidemiological research

This paper reviews the epidemiological literature on Alzheimer's disease. Increasing age emerges as one of the most powerful risk factors for the development of dementia/Alzheimer's disease across all populations studied. Examination of age-independent risk factors suggests that there are few environmental or clinical factors that seem to be related consistently to increased risk of dementia/Alzheimer's disease. In contrast, familial/genetic risk factors do seem to influence the incidence of dementia/Alzheimer's disease. Age, ethnicity and gender all have been found to moderate the effects of both genetic and environmental risk factors. The overall weight of evidence suggests that the primary influence of both risk and protective factors is to modify rather than determine the expression of dementia during the course of the adult lifespan.